Amos bboadnax



(No Model.)

A. BROADNAX.

DRIVE SCREW. No. 320,329. Patented June 16, 1885.

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NHED

AMOS BROADNAX, or BROOKLYN, NEW YORK, ASSIGNOR To ALBERT O. LEWIS, OF SAME PLACE.

DRIVE-SCREW.

SPECIFICATION forming part of Letters Patent No. 320,329, dated-Tune 16, 1885.

Application filed May 31, 1884.

To all whom it may concern.-

Be it known that l, AMOS BROADNAX, a citizen of the United States, residing in Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Lag, Vood, or Drive Screws, of which the following is a description in such full, clear, concise, and exact terms as will enable any one skilled in the arts to which my invention appertains to make and use the same, reference being had to the accompanying drawings, making part of this specification, and to the letters and figures of reference marked thereon.

My invention relates to improvements in wood-screws, and has especial reference to that form of screws known as drive-screws which are designed to be driven into the wood with a hammer,like an ordinary spike or nail, and to be withdrawn by revolution on their axes, like an ordinary screw. Said improvement consists in providing such screws with points possessing certain features of novelty, which will be hereinafter fully described.

In the accompanying drawings, Figures 1 and 2 are both side elevations of screws embodying my invention.

Similar letters of reference indicate correspondingparts in both figures ofthe drawings.

Referring to Fig. 1, a is the head of a screw of any desired shape; I), the usual blank space above the threads, and c the threads thereof. In this figure a screw is represented having a drive thread, between the convolutions of which blank cylindrical spaces e are included. 9 is a blank space of the same, or nearly the same, diameter as the shank of the screw, not including the threads, and d a tapering point formed thereon, which may be conical or conoidal, or any other desired form.

(No model.)

The screw illustrated in Fig. 2 of the drawings isa slightly modified form of that shown in Fig. 1, differing from that screw only in the omission of the blank spaces e between the convolutions of the threadsthat is to say, in Fig. 2 the slope of each thread rises immediately from thetop of the preceding threadthe circumference of the blank space 9 in this screw being the same, or nearly the same, as that of the smallest circle of the threads.

The length of the lower cylindrical blank space, 9, and the taper and form of the point d are matters to be determined by experience. These screws may be used with or without fir t boring holes in the wood for their reception, and in either case insure a proper alignment, and enter without materially l'acerating the fibres whereby the screw is gripped and held firmly in the wood, and cannot be easily withdrawn exceptby revolution on its aXis, as will be readily understood.

I am aware that drive-screws have been heretofore made with threads of substantially the character illustrated, and with points the base of which are equal in diameter to the external circle of the threads; but

WVhat I claim and desire to secure by Letters Patent is A lag, wood, or drive screw having a ratchet-thread and a tapering or conoidal point, the base of which is of the same diameter as the core of the screw at the bottom of the thread, and a cylindrical part between the base of the point and the commencement of the thread, substantially as and for the purposes described.

AMOS BROADNAX.

WVitnesses:

J. EDGAR BULL, WM. H. BROADNAX. 

